The present invention relates to a crawler device provided in a crawler type of construction vehicle, a vehicle for traveling on an irregular ground, or the like.
FIG. 45 is a side view of a construction vehicle 2 having a crawler device in a triangular form. An upper revolving superstructure 4 is mounted on a vehicle body 3 of the vehicle 2, and a working machine 5, having a bucket or the like, is attached on the upper revolving superstructure 4. The crawler devices 1 of triangular form, being traveling devices, are respectively provided at the front and the rear, and at the right and the left portions of the vehicle body 3. Specifically, a pair of right and left crawler devices 1A and 1A, coupled to a steering device and a driving steering device and a driving device, are disposed at the front part of the vehicle body 3; and a pair of right and left crawler devices 1B and 1B, coupled to the driving device, are disposed at the rear part of the vehicle body 3. In order to make the explanation understandable, the crawler devices 1A are taken as a pair of right and left crawler devices coupled to the steering device and the driving device, and the crawler devices 1B are taken as a pair of right and left crawler devices coupled to the driving device. Further, the crawler devices 1A and/or the crawler devices 1B are collectively called the crawler device 1.
The details of the crawler device 1 having a triangular form are disclosed in, for example, Japanese Laid-open Patent No. 4-8682. This will be explained with reference to FIG. 46. FIG. 46 is a sectional view of the rear end crawler device 1B taken along the Axe2x80x94A line in FIG. 45.
A sprocket 12, rotationally driving a crawler belt 11, is fixedly provided on the external perimeter of the outside end portion of a wheel hub 31, which is on a side of the vehicle body 3 and is free to rotate. A bracket 13 is rotatably attached to the wheel hub 31 via a bearing 32. A truck frame 15, equipped with a roller 14, is fixedly provided at the lower portion of the bracket 13. The front end crawler device 1A has the same configuration as above, and both of the crawler devices 1A and 1B are free to swing about the respective sprocket 12. Each of the crawler devices 1 is supported on the vehicle body 3 by means of a suspension mechanism (not illustrated). Specifically, in the vehicle 2, each crawler device 1 not only is in four-point contact with a road surface, but also can be evenly in contact with even an irregular ground surface with the aforesaid swing function of the crawler device 1.
The truck frame 15 of the aforesaid crawler device 1 in a triangular form has a recoil spring 17 at almost the center portion between a front end idler 16A and a rear end idler 16B as shown in a schematic diagram in FIG. 47. When the front end idler 16A receives a large impactive force from the front, the recoil spring 17 contracts and the front end idler 16A moves to the position shown by an alternate long and two short dashes line to thereby absorb the impactive force.
However, the aforesaid conventional crawler device 1 has the following disadvantages.
(1) The vehicle body 3 is supported by the truck frame 15 by means of the bearing 32, which is placed nearer to the side of the vehicle body 3 than to the sprocket 12. However, the bearing 32 is fitted onto the wheel hub 31. Specifically, the bearing 32 is not provided on an axle beam (not illustrated) and the vehicle body 3 itself, and dose not support the vehicle body 3. The wheel hub 31 is a rotary body for transmitting a rotational force to the sprocket 12. Accordingly, unless the wheel hub 31 is constructed to have higher strength, there is a disadvantage in that the vehicle body 3 is difficult to be supported while smoothly transmitting the rotational force to the sprocket 12. It is extremely disadvantageous for a working vehicle with heavy weight like the machines cited as an example. When the wheel hub 31 is highly strengthened, the wheel hub 31 is inevitably increased in size. Specifically, there is a disadvantage in that the vehicle height is difficult to be lowered.
(2) The wheel hub 31 is placed nearer to the vehicle body 3 than to the sprocket 12. Therefore in a large-sized vehicle which contains a reduction gear such as a planetary gear train or the like, the configuration of the small space between the right and left sprockets 12 and 12 is complicated. Accordingly, there are disadvantages in that the vehicle height is difficult to be lowered, in that the distance between the sprockets 12 and 12 is difficult to be shortened (specifically, the vehicle width is difficult to be reduced), and in that the maintainability of the wheel hub 31 is worsened.
(3) The crawler device 1 is free to swing about the sprocket 12. For this reason, as shown in FIG. 48, there is a disadvantage in that the front part of the front end crawler device 1A faces downwardly (specifically, stumbles) when the vehicle 2 collides with an obstacle 6 in the front. The crawler device 1 is always free to swing; therefore, there is a disadvantage in that when an operation is carried out with the working machine 5, the crawler device 1 swings, depending on the variations in the load on the working machine 5, and on road conditions; and an operation to be carried out while standing firm cannot be carried out. Specifically, there is a disadvantage of unsatisfactory stability during operation.
The present invention is made to eliminate the aforesaid disadvantages of the prior art, and its object is to provide a crawler device for a crawler type vehicle with a simple structure, which lowers the vehicle height, decreases the vehicle width, has excellent maintainability, does not stumble even when colliding with an obstacle during traveling, and provides superior operation stability in a working vehicle.
A first configuration of a crawler device for a crawler type vehicle according to the present invention is, in a crawler type vehicle including, on the right and the left sides of either one of a front or a rear portion or both of the front and the rear portions of a vehicle body, crawler devices, each having a sprocket being a driving wheel, an idler being a driven wheel disposed on a truck frame, and a crawler belt passed around the sprocket and the idler, characterized by including a front end link, coupled to a forward part of the truck frame by means of a pin at a lower end portion thereof and to the vehicle body side by means of a pin at the upper end portion thereof, and a rear end link, coupled to a rearward part of the truck frame by means of a pin at the lower end portion thereof and to the vehicle body side at a position behind the front end link by means of a pin at the upper end portion thereof.
According to the first configuration, when an external force in a fore-and-aft direction is exerted on the truck frame, the truck frame can swing in the fore-and-aft directions, supported by the front link and the rear link. Accordingly, when the idler collides with an obstacle during traveling, the truck frame swings rearwardly and absorbs the impact. For this reason, the conventional recoil spring becomes unnecessary, thereby simplifying the configuration.
A second configuration is, in the aforesaid first configuration, characterized by the sprocket being disposed on either one of the front or the rear portion of the truck frame, and the idler being disposed on the other one of the front or the rear portion of the truck frame. According to the second configuration, in addition to the operational effects in the first configuration, a so-called low drive configuration is established. Specifically, the vehicle height can be lowered, and the position of the center of gravity is lowered, thereby improving the stability.
A third configuration is, in a crawler type vehicle including, on the right and left sides of either one of a front or a rear portion or both of the front and the rear portions of a vehicle body, crawler devices each having a sprocket being a driving wheel, a front end idler and a rear end idler being driven wheels respectively disposed at the front and the rear positions of a truck frame disposed under the sprocket, and a crawler belt passed around the sprocket, the front end idler, and the rear end idler, characterized by including:
a front end link, coupled to a forward part of the truck frame by means of a pin at a lower end portion thereof and to the vehicle body side by means of a pin at the upper end portion thereof, and a rear end link, coupled to a rearward part of the truck frame by means of a pin at the lower end portion thereof and to the vehicle body side at a position behind the front end link by means of a pin at the upper end portion thereof.
In the aforesaid third configuration, the crawler device is specified to be in a triangular form compared to the aforesaid first configuration. Consequently, according to the third configuration, the same operational effects as in the first configuration are obtained.
A fourth configuration is, in the aforesaid first or the third configuration, characterized by a quadric link structure, which is formed by the vehicle body, the truck frame, the front end link, and the rear end link, having a side length on the truck frame side shorter than a side length on the vehicle body side. According to the fourth configuration, when the idler, or one of the front end idler and the rear end idler collides with an obstacle while the vehicle is traveling, the truck frame swings in such a way that the front portion of the truck frame moves upwardly, and the rear portion of the truck frame moves downwardly. Accordingly, the device can pass over the obstacle without stumbling thereon. Specifically, traveling performance on an irregular ground is improved.
A fifth configuration is, in the aforesaid fourth configuration, characterized by a point of intersection of an axis of the front end link and an axis of the rear end link being located inside the loop of the endless crawler belt. According to the fifth configuration, the point of intersection is located inside the loop of the crawler belt; therefore, the swing of the crawler device is increased.
A sixth configuration is, in the aforesaid first or third configuration, characterized by either one or both of the front end link and/or the rear end link being of an extension type comprising of a turn buckle type, a grease cylinder type, or the like. According to the sixth configuration, the link is extended in a normal situation, and is contracted at the time of attaching and detaching the crawler belt, thereby facilitating the operation of attaching and detaching the crawler belt.
A seventh configuration is, in the aforesaid first or third configuration, characterized by upper rollers, which are allowed to rotate in contact with the inner side surface of the upper part of the endless crawler belt, being respectively provided at two positions on the vehicle body side corresponding to positions at the forward and rearward parts of the truck frame. Conventionally, when the crawler device collides with an obstacle and the crawler device swings, the crawler belt is slightly loosened. However, according to the seventh configuration, even if the crawler device swings, the upper rollers lift the crawler belt from the inside thereof; therefore, the crawler belt is not loosened. Specifically, the crawler belt is tightened. Accordingly, stability can be maintained during traveling.
An eighth configuration is, in the aforesaid first or third configuration, characterized by further including an arm which is provided at the position on the vehicle body side corresponding to a position which is above the crawler belt and on a vertical line passing through almost the center of a distance from the upper end portion of the front end link to the upper end portion of the rear end link, with the center of the arm being free to swing in a vertical direction and the length thereof being in a fore-and-aft direction, and rollers respectively provided on the front end portion and the rear end portion of the arm, with the rollers being provided to be pressed against the crawler belt downwardly from the upper surface of the crawler belt. According to the eighth configuration, even if the crawler device swings, either of two rollers presses the crawler belt downwardly from the outside; therefore, the crawler belt is not loosened. Specifically, the crawler belt is tightened. Consequently, stability can be maintained during traveling. Especially in the eighth configuration, the crawler belt is always pressed toward the sprocket side; therefore, skipping pitch and separation of the crawler belt on the sprocket is prevented, and the traveling performance is improved.
A ninth configuration is, in the aforesaid first or third configuration, characterized by either one of the front end link, coupling with the pins at the upper and the lower end portions of the front end link, or the rear end link, coupling with the pins at the upper and the lower end portions of the rear end link, being an elastic member fixedly provided at either one or both of the vehicle body side and/or the truck frame. According to the ninth configuration, one side is supported by the elastic member while the other side is coupled by the link; therefore, even if the front end idler collides with an obstacle during traveling, the truck frame swings rearwardly, and the rear end idler moves downwardly, thereby establishing the position to pass over the obstacle, and the traveling performance on an irregular ground is improved. Even if the device collides with the obstacle, the elastic member absorbs the impactive force.
A tenth configuration is, in a crawler type vehicle including, on right and left sides of either one of a front or a rear portion or both of the front and the rear portions of a vehicle body, crawler devices each having: a sprocket, being a driving wheel, which is supported by means of a bearing provided at the vehicle body side; a front end idler and a rear end idler, being driven wheels respectively disposed at the front and the rear positions of a truck frame disposed under the sprocket; and a crawler belt passed around the sprocket, the front end idler, and the rear end idler; characterized by including an extendedly provided member which is provided to extend from the vehicle body side over the sprocket to the outside thereof, with the bearing being provided at the extendedly provided member.
According to the tenth configuration, a wheel hub with a complicated structure or the like can be disposed on the outside of the vehicle, and the sprocket can be supported at both ends. Accordingly, the small space between the sprockets can be simplified. Specifically, the vehicle height can be lowered, and the vehicle width can be decreased. Consequently, entry into a narrow path is facilitated and the transportability is improved. If the wheel hub with a complicated structure is provided outside, maintainability is improved.
An eleventh configuration is, in the aforesaid tenth configuration, characterized by further including a front end link, coupled to a forward part of the truck frame by means of a pin at a lower end portion thereof and to the vehicle body side by means of a pin at the upper end portion thereof, and a rear end link, coupled to a position at a rearward part of the truck frame by means of a pin at the lower end portion thereof and to the vehicle body side at a position behind the front end link by means of a pin at the upper end portion thereof. The feature of the aforesaid eleventh configuration corresponds to the feature of the aforesaid first configuration. Consequently, according to the eleventh configuration, the same operational effects as provided by the first configuration are obtained.
A twelfth configuration is, in the aforesaid second configuration, characterized by the truck frame having at least one roller at the lower portion thereof between the idler and the sprocket, the crawler belt having tread surfaces in a protrusion form at a predetermined pitch spaced with a predetermined gap, to be trod by the idler, the sprocket, and the roller; and a space between the idler and a roller adjacent to the idler, a space between the sprocket and a roller adjacent to the sprocket, and a space between the idler and the sprocket being respectively expressed by
[(0.5xc2x10.2)+N]xc3x97Lp 
if N is set as zero or a natural number, and Lp is set as a crawler belt pitch.
Further, a thirteenth configuration is, in the aforesaid third or tenth configuration, characterized by the truck frame having at least one roller at the lower portion thereof between the front end idler and the rear end idler, the crawler belt having tread surfaces in a protrusion form at a predetermined pitch spaced with a predetermined gap to be trod by the front end idler, the rear end idler, and the roller; and a space between the front end idler and a roller adjacent to the front end idler, a space between the rear end idler and a roller adjacent to the rear end idler, and a space between the front end idler and the rear end idler being respectively expressed by
[(0.5xc2x10.2)+N]xc3x97Lp 
if N is set as zero or a natural number, and Lp is set as a crawler belt pitch.
According to the twelfth and the thirteenth configurations, even when any one of the idlers (or the front side idler and the rear side idler), the sprocket, and the rollers are positioned on the predetermined gap of the crawler belt and is to fall in the predetermined gap, all of the others ride on the tread surface. Accordingly, the occurrence of greater pitching of the crawler device, based on the aforesaid predetermined gap, can be prevented. Specifically, the vibration during traveling is decreased; therefore, riding comfort is improved.
A fourteenth configuration is, in any one of the aforesaid first, third, and tenth configurations, characterized by either or both of a swing stopping mechanism, for stopping the swing of the truck frame at any position, and/or a swing control mechanism, for controlling the maximum swing of the truck frame, being provided between the vehicle body side and the truck frame. According to the fourteenth configuration, the swing of the crawler device can be stopped at any position by using the swing stopping mechanism. If the swing control mechanism is used, the unlimited swing of the crawler device is eliminated. Specifically, if the vehicle body is, for example, a construction machine or the like equipped with an excavator or the like, and when the operation is carried out, the vehicle is stopped, and in this situation, the swing stopping mechanism is applied. Thus the crawler device maintains an angle of swing at the time of stopping the vehicle irrespective of variations in the load or the road conditions. Consequently, standing firm operations can be carried out. Specifically, stability is secured in carrying out an operation.
A fifteenth configuration is, in any one of the aforesaid first, third, and tenth configurations, characterized by the endless crawler belt being made of rubber and having a plurality of raised portions at predetermined pitches on the inner center portion thereof in a direction to be passed around, the sprocket having a plurality of engaging gears with the raised portions on the outer perimeter and having cylinder members, which are fixedly provided on the right and the left sides of the engaging gears and allow the outer perimeter surface thereof to abut the surface surrounding the raised portions, and an external diameter of the sprocket being smaller than an external diameter of the top of the engaging gear.
According to the fifteenth configuration, when the raised portions of the crawler belt are meshed with the engaging gears of the sprocket, the engaging gears are engaged in the bottom surface and the side surface of respective raised portions by xe2x80x9c(the external diameter of the top of the engaging gearxe2x88x92the external diameter of the sprocket)/2xe2x80x9d. At the same time, the external perimeter surfaces of the cylinder members forcefully contact the surface surrounding the raised portions of the crawler belt. Accordingly, the crawler belt obtains a rotational driving force from the sprocket. Accordingly, a light weight crawler belt, without core metals or the like, can be used for the crawler belt. Consequently, the sprocket can transmit a highly efficient rotational force to the crawler belt. Specifically, higher tractive force can be obtained; the crawler belt is difficult to fall off by the engaging amount 5; skids are difficult to occur; and the size, the noise, and the cost can be reduced.